default file type for wireshark packet capture

For example, the standard tool TcpDump will by default use a SnapLen of 68 bytes for IPv4 packets and 96 bytes for IPv6 packets.

Other network capturing tools often also support this type of capturing. When this feature is used, it might not be possible to do reassembly of higher-level packets split across link-layer packets, such as IP_Reassembly, any more. The drawback is that packets that are longer than the SnapLen will be truncated and not all the data from these packets will be saved in the capture file.

The benefit from using this feature is that long capture files will take up much less space than if SnapLen is not specified, and less CPU time and bus bandwidth will be used copying packets and saving them to a file, so fewer packets might be dropped. This feature can be enabled when you start the capture by the controls in the capture dialog: In this case it may be useful to reduce the total amount of storage used by the capture file by limiting the amount of data from each frame that is actually saved. This is sometimes called PacketSlicing.īy default, both Wireshark and TShark will capture the entire content of the packet as it was received across the wire however, this can generate very large files for very long captures. SnapLen, Snap Length, or snapshot length is the amount of data for each frame that is actually captured by the network capturing tool and stored into the CaptureFile.

Default file type for wireshark packet capture